Django - Can you use property as the field in an aggregation function?

django django-models django-aggregation
orokusaki picture orokusaki · Jun 18, 2010 · Viewed 8.1k times · Source

I know the short answer because I tried it. Is there any way to accomplish this though (even if only on account of a hack)?

class Ticket(models.Model):
    account = modelfields.AccountField()
    uuid = models.CharField(max_length=36, unique=True)
    created = models.DateTimeField(auto_now_add=True)

    class Meta:
        ordering = ['created']

    @property
    def repair_cost(self):
        # cost is a @property of LineItem(models.Model)
        return self.lineitem_set.aggregate(models.Sum('cost'))

Answer

Ignacio Vazquez-Abrams picture Ignacio Vazquez-Abrams · Jun 18, 2010

No. Anything that goes through a built-in manager has to be a real field, since they only touch the database. In order to work with a property they'd have to turn every record in the table into a model, then filter through them in Python.

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